The curing of monomeric materials to produce polymeric thermoset resins is well known in the art. In general, the curable monomers have one and customarily more than one active group which serves as a reactive site for the curing or crosslinking polymerization to produce a crosslinked polymer. However, for efficient curing of many or most polymerizable monomers to produce crosslinked resins, for example the curing of an epoxy resin, the presence of a curing agent, catalytic or stoichimetric, is required to cuase the curing or crosslinking to occur at an acceptable rate. Even in the presence of most curing agents the rate of curing is undesirably slow and the addition of an accelerator is required to obtain sufficiently rapid curing. Certain polymerizable monomers do cure in the absence of added curing agent or accelerator but only upon the application of high intensity energy, e.g., UV light.
There are, however, other monomeric materials which contain one or more active sites such that no curing will take place upon application of heat. One class of such crosslinked resin precursor includes within the molecular structure one or more moieties of an arylcyclobutene, particularly a benzocyclobutene. Without wishing to be bound by any particular theory, it appears likely that upon application of heat the cyclobutene moieties undergo ring-opening to produce reactive intermediates which react with active portions of adjacent molecules. The resulting resin have properties of rigidity and resistance to many common solvents.
A series of U.S. patents to Krichoff, of which U.S. Pat. No. 4,540,763 is illustrative, describes the production and curing of a large number of benzocyclobutene derivatives including multi-cyclic aromatic compounds in which the aromatic rings are directly connected, or connected by a functional group, to a carbon atom of the six-membered ring of a benzocyclobutene moiety. These derivatives are said to be self-curing. It would be of advantage, however, to provide a novel class of self-curing benzocyclobutene-type compounds of a different molecular structure.